Oh in 2018 out of the top 5 net worth players in tennis which includes tournament winnings and endorsements, 3 were women. Out of the top 10, 6 were women. So apparently sponsors, advertisers, and tournaments do think women are on par with men in global earnings. Again, bringing in tennis does not work for your argument, it is a different animal than soccer. Individual sports are not the same in earnings as team sports.
What you are really pointing out is the lack of depth in the women's game, coupled with above-market payouts for slams. A handful of women have made out like bandits.
They see this pot of gold being threatened by trans women. Martina Navratilova has pointed this out and been viciously attacked by the gay Nazis, ironic since she was probably the first openly gay sports star. No doubt current players realize the threat but are intimidated from speaking out. The USTA is a hotbed of gay activism, so it will be interesting to see how they handle it.
